26 CFR §301.7517-1

1. (a)In general. Section 7517 requires the Service to furnish to a taxpayer, at the request of that taxpayer, a statement explaining the estate, gift or generation-skipping transfer valuation of any item contained on a return filed by the taxpayer as to which a determination or proposed determination of value has been made. The request must be filed no later than the latest time to file a claim for refund of the tax which is dependent on the value with respect to which the determination has been made. The request should be filed with the district director's office that has jurisdiction over the return of the taxpayer.
2. (b)Effective date
   1. (1)Estates of decedents. Section 7517 applies to estates of decedents dying after December 31, 1976.
   2. (2)Gifts. Section 7517 applies to gifts made after December 31, 1976.
   3. (3)Generation-skipping transfer. Section 7517 applies to any generation-skipping transfer subject to chapter 13.